Aviation display depiction of weather threats

ABSTRACT

A method for indicating a weather threat to an aircraft is provided. The method includes inferring a weather threat to an aircraft and causing an image to be displayed on an aviation display in response to a determination by aircraft processing electronics that the inferred weather threat to the aircraft is greater than a measured weather threat to the aircraft.

BACKGROUND

The present disclosure relates generally to the field of airborne radar systems. The present disclosure more specifically relates to the field of depiction of inferred weather threats on an aviation display.

In general, an airborne weather radar can readily detect precipitation (e.g., rain), which may be used as a surrogate for weather threats to an aircraft. However, some storms (e.g., typhoons) produce significant rainfall but little lightning, hail, turbulence, or other threats to the aircraft; whereas, other weather cells may produce little precipitation but severe turbulence. Similarly, lightning detectors can readily detect lightning strikes, but do not indicate areas of high electrical energy around a cell that are not active, but may be induced to strike by the passage of an aircraft.

Current systems which make inferences regarding weather threats are typically ground based and make broad predictions about weather. For example, National Weather Service severe thunderstorm watches or tornado watches indicate that conditions are favorable for a thunderstorm or tornado; however, these watches typically cover hundreds of square miles, which is generally not helpful in making decisions regarding flying through or around specific weather cells. Thus, there is a need to provide an improved system for indicating an inferred weather threat to an aircraft.

SUMMARY

One embodiment relates to a method for indicating a weather threat to an aircraft, the method including inferring a weather threat to an aircraft and causing an image to be displayed on an aviation display in response to a determination by aircraft processing electronics that the inferred weather threat to the aircraft is greater than a measured weather threat to the aircraft.

Another embodiment relates to an apparatus for indicating an inferred weather threat to an aircraft, the apparatus including processing electronics configured to cause an image to be displayed on an aviation display in response to a determination that an inferred weather threat to the aircraft is greater than a measured weather threat to the aircraft.

Another embodiment relates to an aircraft weather radar system, the system including a processing circuit configured to determine a first weather threat using an algorithm using one of 1. a wind speed, a wind direction, and a size of a weather cell, 2. a temperature and a reflectivity, 3. a temperature and a reflectivity as a function of altitude, and 4. a change in an altitude of an echo top of a weather cell over time. The processing circuit is configured to cause an image to be displayed on an aviation display in response to the first weather threat to the aircraft being greater than a measured weather threat to the aircraft.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of an aircraft control center, according to an exemplary embodiment.

FIG. 2 is a schematic illustration of the nose of an aircraft including a weather radar system, according to an exemplary embodiment.

FIG. 3 is a block diagram of a weather radar system, according to an exemplary embodiment.

FIG. 4 is a block diagram of the processing electronics of the weather radar system of FIG. 3, according to an exemplary embodiment.

FIGS. 5A and 5B are schematic illustrations of an aviation display showing unmodified and modified radar returns, respectively, in response to an inferred core threat assessment, according to an exemplary embodiment.

FIGS. 6A and 6B are schematic illustrations of an aviation display showing an inferred overflight threat assessment and a corresponding view from the aircraft control center, respectively, according to an exemplary embodiment.

FIG. 7 is a schematic illustration of an aviation display showing an inferred electrified region around a weather cell, according to an exemplary embodiment.

FIGS. 8A and 8B are schematic illustrations of an aviation display showing an inferred high altitude threat and a corresponding view from the aircraft control center, respectively, according to an exemplary embodiment.

FIG. 8C is a schematic illustration of an aviation display showing an inferred high altitude threat, according to another embodiment.

FIG. 9 is a flowchart of a process for indicating a weather threat to an aircraft, according to an exemplary embodiment.

FIG. 10 is a flowchart of a process for indicating a weather threat to an aircraft, according to another embodiment.

DETAILED DESCRIPTION

Referring generally to the FIGURES, systems and methods for indicating a weather threat to an aircraft are described, according to an exemplary embodiment. An airborne weather radar system is generally configured to project radar beams and to receive radar returns relating to the projected radar beams. The projected radar beams generally pass through air and reflect off of precipitation (e.g., rain, snow, etc.), other aircraft, and terrain (e.g., a mountain, a building). Using the reflected return data, processing electronics associated with the weather radar system can distinguish between types of precipitation and terrain. Weather radar systems are typically configured to display the precipitation as measured weather threats in green (light rain), yellow (moderate rain), and red (severe rain). While this “rain gauge” provides valuable information to the crew, it is not an accurate indicator of weather threat to the aircraft. For example, tropical cyclones or typhoons produce tremendous amounts of rain, but they are generally not threatening to an aircraft because they typically do not produce turbulence, hail, or lightning.

To provide a more accurate weather threat assessment to the crew, other threats to the aircraft may be inferred. For example, a core threat assessment (e.g., the probability of hail or lightning within a weather cell) may be inferred based on reflectivity as a function of altitude. A predictive overflight threat assessment may be inferred based on the growth rate and direction of a weather cell below the aircraft. Electrified regions associated with weather cells may not contain precipitation or be actively producing lightning; however, these threatening regions may be inferred based on reflectivity and the temperature at which the reflectivity is occurring. Weather threats (e.g., turbulence, lightning, hail, etc.) associated with the blow off (e.g. anvil) region downwind of a weather cell may be inferred based on wind speed, wind direction, and size of the weather cell. The systems and methods described below cause an image to be displayed on an aviation display in response to a determination that the inferred weather threat to the aircraft is greater than the measured weather threat to the aircraft.

Referring now to FIG. 1, an illustration of an aircraft control center or cockpit 10 is shown, according to an exemplary embodiment. Aircraft control center 10 includes flight displays 20 which are generally used to increase visual range and to enhance decision-making abilities. In an exemplary embodiment, flight displays 20 may provide an output from a radar system of the aircraft. For example, flight displays 20 may provide a top-down view, a horizontal view, or any other view of weather and/or terrain detected by a radar system on the aircraft. The views of weather may include monochrome or color graphical representations of the weather. Graphical representations of weather may include an indication of altitude of those objects or the altitude relative to the aircraft. Aircraft control center 10 may further include other user interface elements such as an audio device 30 (e.g., speaker, electro-acoustic transducer, etc.) and illuminating or flashing lamps 40.

Referring to FIG. 2, the front of an aircraft 101 is shown with aircraft control center 10 and nose 100, according to an exemplary embodiment. A radar system 300 (e.g., a weather radar system or other radar system) is generally located within nose 100 of aircraft 101 or within aircraft control center 10 of aircraft 101. According to various exemplary embodiments, radar system 300 may be located on the top of aircraft 101 or on the tail of aircraft 101 instead. Radar system 300 may include or be coupled to an antenna system. A variety of different antennas or radar systems may be used with the present invention (e.g., a split aperture antenna, a monopulse antenna, a sequential lobbing antenna, etc.).

Radar system 300 generally works by sweeping a radar beam horizontally back and forth across the sky. Some radar systems will conduct a first horizontal sweep 104 directly in front of aircraft 101 and a second horizontal sweep 106 downward at some tilt angle 108 (e.g., 20 degrees down). Returns from different tilt angles can be electronically merged to form a composite image for display on an electronic display shown, for example, in FIG. 1. Returns can also be processed to, for example, distinguish between terrain and weather, to determine the height of terrain, or to determine the height of weather. Radar system 300 may be a WXR-2100 MultiScan™ radar system or similar system manufactured by Rockwell Collins. According to other embodiments, radar system 300 may be an RDR-4000 system or similar system manufactured by Honeywell International, Inc. Radar system 300 may include a terrain awareness and warning system (TAWS) and coordinate with associated user interface elements in aircraft control center 10 (e.g., flashing lights 40, displays 20, display elements on a weather radar display, display elements on a terrain display, audio alerting devices 30, etc.) configured to warn the pilot of potentially threatening terrain features.

Referring to FIG. 3, a block diagram of a weather radar system 300 is shown, according to an exemplary embodiment. Weather radar system 300 is shown to include a weather radar antenna 310 connected (e.g., directly, indirectly) to an antenna controller and receiver/transmitter circuit 302. Antenna controller and receiver/transmitter circuit 302 may include any number of mechanical or electrical circuitry components or modules for steering a radar beam. For example, circuit 302 may be configured to mechanically tilt the antenna in a first direction while mechanically rotating the antenna in a second direction. In other embodiments, a radar beam may be electronically swept along a first axis and mechanically swept along a second axis. In yet other embodiments, the radar beam may be entirely electronically steered (e.g., by electronically adjusting the phase of signals provided from adjacent antenna apertures, etc.). Circuit 302 may be configured to conduct the actual signal generation that results in a radar beam being provided from weather radar antenna 310 and to conduct the reception of returns received at radar antenna 310. Radar return data is provided from circuit 302 to processing electronics 304 for processing. For example, processing electronics 304 can be configured to interpret the returns for display on display 20.

Processing electronics 304 can also be configured to provide control signals or control logic to circuit 302. For example, depending on pilot or situational inputs, processing electronics 304 may be configured to cause circuit 302 to change behavior or radar beam patterns. In other words, processing electronics 304 may include the processing logic for operating weather radar system 300. It should be noted that processing electronics 304 may be integrated into radar system 300 or located remotely from radar system 300, for example, in aircraft control center 10.

Processing electronics 304 are further shown as connected to aircraft sensors 314 which may generally include any number of sensors configured to provide data to processing electronics 304. For example, sensors 314 could include temperature sensors, humidity sensors, infrared sensors, altitude sensors, a gyroscope, a global positioning system (GPS), or any other aircraft-mounted sensors that may be used to provide data to processing electronics 304. It should be appreciated that sensors 314 (or any other component shown connected to processing electronics 304) may be indirectly or directly connected to processing electronics 304. Processing electronics 304 are further shown as connected to avionics equipment 312. Avionics equipment 312 may be or include a flight management system, a navigation system, a backup navigation system, or another aircraft system configured to provide inputs to processing electronics 304.

Referring to FIG. 4, a detailed block diagram of processing electronics 304 of FIG. 3 is shown, according to an exemplary embodiment. Processing electronics 304 includes a memory 320 and processor 322. Processor 322 may be or include one or more microprocessors, an application specific integrated circuit (ASIC), a circuit containing one or more processing components, a group of distributed processing components, circuitry for supporting a microprocessor, or other hardware configured for processing. According to an exemplary embodiment, processor 322 is configured to execute computer code stored in memory 320 to complete and facilitate the activities described herein. Memory 320 can be any volatile or non-volatile memory device capable of storing data or computer code relating to the activities described herein. For example, memory 320 is shown to include modules 328-338 which are computer code modules (e.g., executable code, object code, source code, script code, machine code, etc.) configured for execution by processor 322. When executed by processor 322, processing electronics 304 is configured to complete the activities described herein. Processing electronics 304 includes hardware circuitry for supporting the execution of the computer code of modules 328-338. For example, processing electronics 304 includes hardware interfaces (e.g., output 350) for communicating control signals (e.g., analog, digital) from processing electronics 304 to circuit 302 or to display 20. Processing electronics 304 may also include an input 355 for receiving, for example, radar return data from circuit 302, feedback signals from circuit 302 or for receiving data or signals from other systems or devices.

Memory 320 includes a memory buffer 324 for receiving radar return data. The radar return data may be stored in memory buffer 324 until buffer 324 is accessed for data. For example, a core threat module 328, overflight module 330, electrified region module 332, high altitude threat module 334, display control module 338, or another process that utilizes radar return data may access buffer 324. The radar return data stored in memory 320 may be stored according to a variety of schemes or formats. For example, the radar return data may be stored in an x,y or x,y,z format, a heading-up format, a north-up format, a latitude-longitude format, or any other suitable format for storing spatial-relative information.

Memory 320 further includes configuration data 326. Configuration data 326 includes data relating to weather radar system 300. For example, configuration data 326 may include beam pattern data which may be data that a beam control module 336 can interpret to determine how to command circuit 302 to sweep a radar beam. For example, configuration data 326 may include information regarding maximum and minimum azimuth angles of horizontal radar beam sweeps, azimuth angles at which to conduct vertical radar beam sweeps, timing information, speed of movement information, and the like. Configuration data 326 may also include data, such as threshold values, model information, look up tables, and the like used by modules 328-338 to identify and assess threats to aircraft 101.

Memory 320 is further shown to include a core threat module 328 which includes logic for using radar returns in memory buffer 324 to make one or more determinations or inferences relating to core threats to aircraft 101. For example, core threat module 328 may use temperature and radar return values at various altitudes to calculate a probability that lightning, hail, and/or strong vertical shearing exists within a weather cell. Core threat module 328 may be configured to compare the probability and/or severity of the core threat to a threshold value stored, for example, in core threat module 328 or configuration data 326. Core threat module 328 may further be configured to output a signal to display control module 338 indicative of the probability of the core threat, of the inferred threat level within the weather cell, or of the inferred threat level within the weather cell being greater than the measured threat due to radar returns from rainfall. The signal may further cause a change in a color on aviation display 20 associated to the threat level to aircraft 101.

Memory 320 is further shown to include an overflight module 330 which includes logic for using radar returns in memory buffer 324 to make one or more determinations or inferences based on weather below aircraft 101. For example, overflight module 330 may be configured to determine the growth rate of a weather cell and/or the change in altitude of an echo top of a weather cell over time. Overflight module 330 may further be configured to calculate a probability that a weather cell will grow into the flight path of aircraft 101. Overflight module 330 may be configured to output a signal to display control module 338 indicating the threat of the growing weather cell in relation to the flight path of aircraft 101. For example, the signal may indicate predicted intersection of the flight path of aircraft 101 and the weather cell, rate of growth of the weather cell, or predicted growth of the weather cell to within a threshold distance of the flightpath of aircraft 101. For example, the signal may cause an icon to be displayed on aviation display 20 in a location corresponding to the growing cell, wherein the size of the icon may represent the size, amount, or probability of threat to the aircraft. Overflight module 330 may be configured to inhibit display of weather far below, and thus not a threat to, aircraft 101.

Memory 320 is further shown to include a electrified region module 332 which includes logic for using radar returns in memory buffer 324 to make one or more determinations or inferences regarding potentially electrified regions around the weather cell. For example, electrified region module 332 may be configured to use temperature and reflectivity to determine whether a region around a weather cell is likely to produce lightning. Electrified region module 332 may be configured to determine a probability of aircraft 101 producing a lightning strike if the aircraft flies through a particular region based on the reflectivity around a convective cell near the freezing layer. Electrified region module 332 may further be configured to cause a pattern to be displayed on aviation display 20. For example, electrified region module 332 may be configured to output a signal to display control module 338 indicating the existence, location, and/or severity of risk of the electrified region.

Memory 320 is further shown to include a high altitude threat module 334 which includes logic for using radar returns in memory buffer 324 to make one or more determinations or inferences regarding threats related to a blow off or anvil region of a weather cell. For example, high altitude threat module 334 may be configured to use wind speed, wind direction, and size of a weather cell to predict the presence of an anvil region downwind of a weather cell that may contain lightning, hail, and/or turbulence. High altitude threat module 334 may be configured to cause a pattern to be displayed on an aviation display 20. For example, high altitude threat module 334 may be configured to output a signal to display control module 338 indicating the existence, location, and severity or risk of the anvil region.

Memory 320 is further shown to include a beam control module 336. Beam control module 336 may be an algorithm for commanding circuit 302 to sweep a radar beam. Beam control module 336 may be used, for example, to send one or more analog or digital control signals to circuit 302. The control signals may be, for example, an instruction to move the antenna mechanically, an instruction to conduct an electronic beam sweep in a certain way, an instruction to move the radar beam to the left by five degrees, etc. Beam control module 336 may be configured to control timing of the beam sweeps or movements relative to aircraft speed, flight path information, transmission or reception characteristics from weather radar system 300 or otherwise. Beam control module 336 may receive data from configuration data 326 for configuring the movement of the radar beam.

Memory 320 is further shown to include a display control module 338 which includes logic for displaying weather information on aviation display 20. For example, display control module 338 may be configured to display radar return information received from memory buffer 324 and to determine a gain level or other display setting for display of an inferred threat to aircraft 101 on a weather radar display. Display control module 338 may be configured to receive signals relating to threats to aircraft 101 from core threat module 328, overflight module 330, electrified region module 332, and high altitude threat module 334. Display control module 338 may further be configured to cause, in response to one or more signals received from threat modules 328-334 and threshold values from configuration data 326, a change in color of a portion of an image on aviation display 20, a pattern to be overlaid on an image on aviation display 20, and an icon to be shown on aviation display 20. Display control module 338 may be configured to cause a change in size, location, shape, or color of the colored regions, patterns, and/or icons in response to updated signals received from modules 328-336.

Processing electronics 304 may be configured to use none, some, or all of the threat modules 328-334 described above. For example, processing electronics 304 may have an automatic mode, in which weather radar antenna 310 is automatically controlled (e.g., direction, gain, etc.) and core threat module 328, overflight module 330, electrified region module 332, and high altitude threat module 334 are all processing information looking for inferred threats. Processing electronics 304 may have a manual mode, in which one or more of core threat module 328, overflight module 330, electrified region module 332, and high altitude threat module 334 may be disabled, for example, for diagnostic purposes.

Referring now to FIGS. 5A and 5B, schematic illustrations of aviation display 20 showing unmodified and modified radar returns, respectively, in response to an inferred core threat assessment are shown, according to an exemplary embodiment. Processing electronics 304 may be configured to cause aviation display 20 to show measured threats to aircraft 101. For example, in FIG. 5A, light rain is shown as stippled regions 502 a, which is often indicated with a green color. Regions 504 a (shown as cross-hatched) indicate moderate rain, and are usually colored yellow to indicate caution to the crew. Regions 506 a (shown as solid black) indicate heavy rain, and are usually colored red to indicate warning to the crew. Generally, a crew will always fly through green regions 502, always avoid red regions 506, and use their best judgment on yellow regions 504. In the example shown, a crew heading northeast may decide to bank right and fly through regions 508 a rather than climbing or banking left to avoid the weather cell directly in front of aircraft 101.

As described above, processing electronics 304 uses avionics and radar return information to infer a core threat. For example, high reflectivity above the freezing layer indicates a high probability of strong vertical shearing in the middle of the weather cell, which in turn indicates a high probability of hail and/or lightning. According to one embodiment, core threat module 328 may provide a core threat probability to display control module 338, which would be configured to interpret the probability signal and adjust the color of the image displayed on aviation display 20 accordingly. According to another embodiment, core threat module 328 may compare the probability of the core threat to a threshold value and provide a threat level signal to display control module 338. Display control module 338 may then adjust the color shown on aviation display 20 to represent the threat to the aircraft. For example, referring to FIG. 5B, the core threat levels in regions 502 b do not exceed the moderate or yellow threshold; thus regions 502 b remain colored green. Similarly, the core threat levels in regions 504 b do not exceed the high or red threshold and, therefore, remain colored yellow. Regions 506 b are already at the highest threat level, so the regions 506 b remain red. Referring to regions 508 b, processing electronics 304 has inferred a core threat level greater than the high or red threshold. Accordingly, processing electronics 304 has caused the color of regions 508 b to change from yellow to red. Similarly, processing electronics 304 has inferred the core threat in region 510 b to be a moderate threat and, thus, caused the region 510 b to change from no threat indication to yellow. Armed with this inferred core threat information, a crew heading northeast will likely not pass through regions 508 b or 510 b, instead climbing over the cells or banking left to go around the cells.

In the example above, the image of an increased threat was displayed in response to a determination that the inferred weather threat was greater than the measured weather threat to the aircraft. It is contemplated, however, that an inference of a lower core threat may cause the color level to be reduced. For example, regions 506 a indicate heavy rainfall, which is in and of itself not a threat to aircraft 101. If the core threat inference in region 506 a is low, region 506 b may be reduced to a moderate or yellow threat level. It is further contemplated that regions 508 b of inferred core threat may be displayed as a pattern (e.g., striped pattern, speckled pattern, checkerboard pattern, etc.) of the increased threat level color in order to indicate to the crew that the increased threat level is an inference.

Referring FIGS. 6A and 6B, schematic illustrations of aviation display 20, showing an inferred overflight threat assessment and a corresponding forward view through the windshield of aircraft 101 from aircraft control center 10, respectively, are shown according to an exemplary embodiment. As shown, processing electronics 304 cause aviation display 20 to display radar returns reflecting off the of the moisture within the weather cells. For example, region 602 a on display 20 corresponds to a weather cell or cloud 602 b seen to the left of FIG. 6B. Similarly, regions 604 a and 606 a correspond to weather cells or clouds 604 b and 606 b, respectively. Cloud 608 b is far below the flight path of the aircraft, and while the current weather within the cells may be severe, it will not effect aircraft 101 (e.g., not be significant to aircraft operations) as the aircraft overflies weather cell 608 b. Thus, processing electronics 304 inhibits display of the weather cell in region 608 a of aviation display 20 to prevent the crew from unnecessarily flying around weather cell 608 b. However, these lower convective cells are often below, and thus obscured, by a stratiform cloud layer (e.g., cloud deck), making it difficult, if not impossible for the crew to see these developing cells. Accordingly, the current weather conditions of weather cell 610 b cause processing electronics 304 to inhibit the display of weather in region 610 a of display 20, an icon 612 may be displayed in region 610 a to indicate that processing electronics 304 has inferred that weather cell 610 b poses a potential hazard to aircraft 101.

Processing electronics 304 may be configured to analyze the growth rate (e.g., the vertical height increase) of a weather cell below aircraft 101. The growth rate may be determined from changes in the altitude of the echo top of weather cell 610 b over time. A probability that weather cell 610 b will grow into the flight path of the aircraft may be calculated by overflight module 330 and compared to a threshold value. As shown in FIG. 6A, icon 612 is overlaid on the image of measured weather on aviation display 20, the size of icon 612 being indicative of the size of threat to aircraft 101. The size of threat may be a function of the probability that the weather cell will grow into flight path, how close the weather cell is predicted to be to the flight path, the growth rate of the cell, and/or the severity of weather within the cell.

According to another embodiment, the growth rate of a weather cell may not be great enough to grow into the flight path of aircraft 101 while cruising. However, as aircraft 101 begins to descend or turn, its flight path may intersect (or nearly intersect) the predicted location of lower developing activity. Accordingly, processing electronics 304 may consider not only the “straight line” flight path of aircraft 101, but the projected flight path of aircraft 101 according to its flight plan or auto-pilot settings. Processing electronics 304 may also cause icon 612 to be displayed for quickly developing severe cells outside of the flight path of aircraft 101, thereby alerting the crew to the presence of these developing cells before they appear as weather on aviation display 20. For example, a series of icons 612 may indicate to the crew that a larger weather system may be developing.

According to an exemplary embodiment, icon 612 is a yellow cautionary icon, which is displayed over black (e.g., no measured weather, weather far below, etc.) regions of the weather image on aviation display 20. Icon 612 may also be displayed on green (light rain, low threat) regions to indicate that the weather cell is rapidly growing and may worsen. According to other embodiments, icon 612 may be a pattern (e.g., striped pattern, speckled pattern, checkerboard pattern, etc.), wherein the pattern may be oriented to indicate a rate or direction of cell growth.

Referring to FIG. 7, a schematic illustration of aviation display 20 showing inferred electrified regions 704 (e.g., electrified regions 704 a, 704 b, 704 c) around a plurality of weather cells (e.g., weather cell 702 a, 702 b, or 702 c) is shown, according to an exemplary embodiment. Processing electronics 304 may be configured to cause images corresponding to the measured rainfall in weather cells 702 and images corresponding to lightning strikes measured with a lightning detector to be displayed on aviation display 20. However, convectivity may generate regions 704 of high electrical potential around weather cells 702, which do not actively produce lightning and, thus, are not measured or displayed as lightning on aviation display 20. As aircraft 101 becomes charged while flying, passage of aircraft 101 through the high voltage region 704 around weather cell 702 may induce a lightning strike through aircraft 101.

Processing electronics 304 may be configured to determine or infer these electrified regions 704 based on reflectivity and the temperature at which the reflectivity is occurring. For example, electrified region module 332 may infer an electrified region based on a reflective region around a convective cell near the freezing layer. Further, electrified regions 704 typically occur at relatively low altitudes (e.g., 10,000 to 25,000 feet), so processing electronics may be configured to further infer electrified regions 704 based on altitude.

In response to an inference of an electrified field, processing electronics 304 may cause a pattern 706 (e.g., speckled pattern, striped pattern, checkerboard pattern, etc.), shown as a speckled pattern, to be overlaid on the image of measured weather on aviation display 20. The size and shape of the pattern 706 may change in response to a change in a level of inferred weather threat to aircraft 101. For example, the shape of the speckled pattern 706 may change with updated radar information.

According to an exemplary embodiment, pattern 706 is yellow to indicate an elevated cautionary threat level. Since electrified regions 704 are typically around the weather cell 702, the yellow pattern 706 is typically displayed over a black region (e.g., no measured weather, very light weather). Yellow pattern 706 may also be displayed over a green region (e.g., light rain, low measured threat) to indicated the elevated inferred threat level. Pattern 706 may be displayed over a yellow region (e.g., moderate rain, medium measured threat level) or a red region (e.g., heavy rain, high measured threat level); however, according to an exemplary embodiment, processing electronics 304 may inhibit pattern 706 from being displayed on yellow or red regions because colors already indicate an equal or higher level of threat. It is contemplated that a red pattern may be displayed over a yellow region in order to indicate an a high probability or intensity of an electrified region in a region of moderate rainfall.

Referring to FIGS. 8A and 8B, schematic illustrations of aviation display 20 showing an inferred high altitude threat and a corresponding forward view through the windshield of aircraft 101 from aircraft control center 10, respectively, are shown according to an exemplary embodiment. Regions 802 a, 804 a, and 806 a shown on aviation display 20 correspond to weather cells or clouds 802 b, 804 b, and 806 b, respectively. Weather cell 806 b is shown to include an anvil 808, which is formed when a cumulonimbus cell has reached the level of stratospheric stability. Anvil 808 spreads downwind of the core of weather cell 806 b and is associated with a variety of threats including turbulence, lightning, and hail lofted out of the top of the cell. These associated threats, as well as anvil 808 itself, tend to have low reflectivity and, therefore, are not displayed as measured weather on aviation display 20. Furthermore, anvil 808 may be on the opposite side of weather cell 806 b from aircraft 101 or may be high above aircraft 101 such that the crew can not easily see the size and location of anvil 808.

Processing electronics 304 may be configured to determine or infer associated threat regions 810 a associated with anvil 808 based on wind speed, wind direction, and the size of the cell. For example, high altitude threat module 330 may infer an associated threat regions 810 a on a downwind side of high altitude, high convectivity cell. In response to an inference of an associated threat region 810 a, processing electronics 304 may cause a pattern 812 (e.g., speckled pattern, striped pattern, checkerboard pattern, etc.), shown as a speckled pattern, to be overlaid on the image of measured weather on aviation display 20. The size and shape of the pattern 812 may change in response to a change in a level of inferred weather threat to aircraft 101. For example, the shape of the speckled pattern 706 may change with updated radar information. According to one embodiment, the stripes of pattern 812 are oriented in the direction of the wind. According to another embodiment, shown in FIG. 8C, processing electronics 304 may cause boxes 814 to be displayed around associated threat regions 810.

As described above with respect to pattern 706, pattern 812 may be yellow to indicate an elevated cautionary threat level. According to an exemplary embodiment, pattern 812 may be displayed or black (e.g., no measured weather, very light weather) or green (e.g., light rain, low measured threat) regions to indicate the elevated inferred threat level; however, pattern 812 may not be displayed over a yellow (e.g., moderate rain, medium measured threat level) or a red (e.g., heavy rain, high measured threat level) region as these regions already indicate an equal or higher level of threat.

Referring to FIG. 9, a flowchart of a process 900 for indicating a weather threat to an aircraft 101 is shown, according to an exemplary embodiment. Process 900 is shown to include the steps of inferring a weather threat to an aircraft 101 (step 902) and causing an image to be displayed on an aviation display in response to a determination by aircraft processing electronics that the inferred weather threat to the aircraft is greater than a measured weather threat to the aircraft (step 904).

Referring to FIG. 10, a flowchart of a process 950 for indicating a weather threat to an aircraft is shown, according to another embodiment. Process 950 is shown to include the steps of determining a measured weather threat to an aircraft based on a rainfall rate (step 952), inferring a weather threat to aircraft 101 based on a wind speed, a wind direction, and a size of a weather cell (step 954), and inferring a weather threat to aircraft 101 based on a temperature and reflectivity (step 955). Process 950 is further shown to include the step of causing, in response to a determination that the inferred weather threat to aircraft 101 is greater than the measured weather threat to aircraft 101, a pattern overlaid on an image indicating the measured weather threat to the aircraft to be displayed on aviation display 20 (step 956). The size and/or the shape of the pattern may be changed in response to a change in a level of inferred threat to aircraft 101 (step 958).

Various alternate embodiments of process 950 are contemplated. Process 950 may not include all of the steps shown. For example, process 950 may not include only one of the steps of inferring a weather threat to aircraft 101 based on a wind speed, a wind direction, and a size of a weather cell (step 954) or inferring a weather threat to aircraft 101 based on a temperature and reflectivity (step 955). According to another embodiment, process 950 may not include the step of changing the size or shape of the pattern in response to a change in a level of inferred weather threat to aircraft 101 (step 958). The steps of process 950 may be performed in various orders. For example, determining measured weather threats (step 952) and inferring weather threats (steps 954, 955) may be performed in any order or simultaneously.

The construction and arrangement of the systems and methods as shown in the various exemplary embodiments are illustrative only. Although only a few embodiments have been described in detail in this disclosure, many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.). For example, the position of elements may be reversed or otherwise varied and the nature or number of discrete elements or positions may be altered or varied. Accordingly, all such modifications are intended to be included within the scope of the present disclosure. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes, and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the present disclosure.

The present disclosure contemplates methods, systems and program products on any machine-readable media for accomplishing various operations. The embodiments of the present disclosure may be implemented using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a hardwired system. Embodiments within the scope of the present disclosure include program products comprising machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a machine, the machine properly views the connection as a machine-readable medium. Thus, any such connection is properly termed a machine-readable medium. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions.

Although the figures may show a specific order of method steps, the order of the steps may differ from what is depicted. Also two or more steps may be performed concurrently or with partial concurrence. Such variation will depend on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the disclosure. Likewise, software implementations could be accomplished with standard programming techniques with rule based logic and other logic to accomplish the various connection steps, processing steps, comparison steps, and decision steps. 

What is claimed is:
 1. A method for indicating a weather threat to an aircraft comprising: determining a precipitation rate based on radar return data; causing an image of a plan view of the precipitation rate to be displayed on an aviation display; inferring a weather threat to an aircraft; determining a first threat level associated with a threat posed to the aircraft by the precipitation rate; determining a second threat level associated with the inferred weather threat; and causing a pattern to be overlaid on the image of the precipitation rate on a location on the aviation display corresponding to the location of the inferred weather in response to a determination by aircraft processing electronics that the second threat level associated with the inferred weather threat to the aircraft is greater than the first threat level associated with the threat posed to the aircraft by the precipitation rate for an airspace corresponding to that location on the aviation display.
 2. The method of claim 1, wherein the pattern comprises a speckled pattern allowing an underlying color of the precipitation rate to show through between the speckles.
 3. The method of claim 1, wherein the weather threat comprises a blow off region; and further comprising inferring the weather threat to the aircraft based on a wind speed, a wind direction, and a size of a weather cell.
 4. The method of claim 3, wherein the inferred weather threat to the aircraft is a region downwind of a cumulonimbus cloud capable of producing at least one of hail, lightning, and turbulence.
 5. The method of claim 1, wherein the weather threat comprises an electrified region; and further comprising inferring the weather threat to the aircraft based on a temperature and reflectivity.
 6. The method of claim 5, wherein the inferred weather threat to the aircraft is an electrified region capable of producing a lightning strike.
 7. The method of claim 1 further comprising changing at least one of the size and shape of the pattern in response to a change in a level of the inferred weather threat to the aircraft.
 8. An apparatus for indicating an inferred weather threat to an aircraft, comprising: processing electronics configured to cause an image of a plan view of a precipitation rate to be displayed on an aviation display base on radar return data, the precipitation rate being shown in the image in at least one color; determine a first threat level associated with a threat posed to the aircraft by the precipitation rate; determine a second threat level associated with an inferred weather threat; and cause the color of at least a portion of the image to be adjusted in response to a determination that the second threat level associated with the inferred weather threat to the aircraft is greater than the first threat level associated with the threat posed to the aircraft by the precipitation rate; wherein the inferred threat comprises at least one of hail and lightning.
 9. The apparatus of claim 8, wherein the processing electronics are configured to cause the color of a portion of the image to be adjusted in response to the probability of at least one of hail and lightning within a weather cell exceeding a threshold value.
 10. The apparatus of claim 8, wherein the processing electronics are configured to cause a portion of the image to change color based on temperature and reflectivity as a function of altitude.
 11. The apparatus of claim 8, wherein the processing electronics are configured to adjust the color of a portion of the image in response to an inference of lightning within a weather cell.
 12. The apparatus of claim 8, wherein the processing electronics are configured to adjust the color of a portion of the image in response to an inference of hail within a weather cell.
 13. An aircraft weather radar system, comprising: a processing circuit configured to: cause a plan view of a precipitation rate to be displayed on an aviation display based on radar return data; determine a first weather threat using an algorithm using one of (1) a wind speed, a wind direction, and a size of a weather cell to infer a blow off region from an anvil; (2) a temperature and a reflectivity to infer an electrified region of airspace; (3) a temperature and a reflectivity as a function of altitude to infer updrafts; and (4) a change in an altitude of an echo top of a weather cell over time to infer whether a weather cell will grow into the path of the aircraft; determine a first threat level associated with a threat posed to the aircraft by the precipitation rate; determine a second threat level associated with the first weather threat; and cause an image to be displayed on the plan view of the precipitation rate on the aviation display in response to the second threat level associated with the first weather threat to the aircraft being greater than the first threat level associated with the threat posed to the aircraft by the precipitation rate.
 14. The system of claim 13, wherein the processing circuit is configured to determine a growth rate of a weather cell below the aircraft.
 15. The system of claim 13, wherein the first weather threat to the aircraft is determined using a probability that a weather cell will grow into the flight path of the aircraft.
 16. The system of claim 15, wherein the image comprises an icon overlaid on the plan view of the measured weather threat to the aircraft, and wherein the size of the icon is representative of a size of the first weather threat.
 17. The system of claim 13, wherein the measured weather threat is based upon rainfall rate.
 18. The method of claim 6, wherein the electrified region is high voltage region that is not active, but may be induced to strike by the passage of the aircraft.
 19. The apparatus of claim 8, wherein adjusting the color of a portion of the image comprises changing the color to a color indicating an increased severity. 